# str1 = '欢迎大家'
# str2 = "哈哈"
# str3 = """MS221_NN"""
# str4 = '''MS221_NN'''
#
# print(type(str1))
# print(type(str2))
# print(type(str3))
# print(type(str4))

str3 = """MS221_NN"""
# # 正数第一个
# print(str3[0])
# print("学号：", str3[1:5])
# # 字符串最后的一个字符
# print(str3[-1])
# # 倒数第二
# print(str3[-2])
# print(str3[-3])
# # 从某个位置开始取到末尾
# print(str3[1:])
# print(str3[:3])
# # 隔一个字符从左往右取值直到结束
# print(str3[0::2])
# 倒序：倒序逻辑都要用反的
# print(str3[-1:-6:-2])
# print(str3[-1::-1])
#
# str4="""MS221_NN"""
# # print(str4[-1::-2])
# # print(str4[::-2])
# print(str4[::])

# 转义符
print("\n", end='\n')
print(r"\n")
print(R"\n")